Asymmetric fission mode in mass 200 region has been looked into by carrying out a systematic study in 197Tl at ~42 MeV excitation energy. The experimental mass distribution reported at this energy does not show any indication of asymmetric fission. However, the semi-empirical Monte-Carlo code GEF predicts a well distinct asymmetric mass split. The present study underlines the importance of N/Z ratio as well as the excitation energy of the fissioning nucleus in determining the onset of asymmetric mass split.

The role of entrance channel parameters, namely the target and projectile deformation, coulomb factor, and the mass asymmetry on the nuclear driving potential, are investigated. Distinct signature of mass drift is observed on the potential landscape across the studied reactions and within the reactions forming the same compound nucleus. The influence of nuclear shells is also reported. No significant structures on the potential energy surface are observed for multi-modal nature of fission. Thus, the driving potential can be employed as a useful probe to study quasi-fission or multi-modal nature of fission.